Conventionally, a radiation-type cooling/heating panel constructed on ceiling has been known. Such a cooling/heating panel has a radiation panel made of a metal or a plaster board; a metallic or resin heat exchange pipe is disposed at a backside of the radiation panel; and this cooling/heating panel is installed on a ceiling. A fluid of a predetermined temperature is flowed in the heat exchange pipe installed on the ceiling, and interior cooling/heating is performed.
As a ceiling cooling/heating panel having a metallic pipe, like a ceiling element disclosed in Patent Document 1, there is the one in which a metallic heat exchange pipe such as copper is mounted on a backside of a ceiling cooling/heating panel. The metallic heat exchange pipe per se has appropriate thermal conductivity; and has high gas barrier properties, so that oxygen does not permeate, or alternatively, circuit components or the like of a connecting portion do not corrode.
On the other hand, the resin heat exchange pipe has a feature that it is well workable, is lightweight, and is low in cost, whereas its thermal conductivity is low in comparison with that of the metallic heat exchange pipe. Therefore, like a ceiling radiation cooling/heating panel disclosed in Patent Document 2, there is proposed the one having a structure in which: a heat exchange pipe is covered with a metallic soaking plate and the heat exchange pipe is held between the soaking plate and a backside of a radiation panel. In this manner, a heat from the heat exchange pipe is efficiently transmitted to the radiation panel.
However, the resin heat exchange pipe has entailed a problem that: gas barrier properties are poor; oxygen contained in air enters a heat exchange medium passing through the heat exchange pipe; and circuit components of a heat exchange medium corrode. Further, a plurality of acoustic absorption holes are perforated and formed on the ceiling cooling/heating panel, and in case of fire, there is apprehension that: flames enter the backside of the radiation panel from the acoustic absorption holes; and the heat exchange pipe burns. Otherwise, there is a danger that: the pipe is melted by a heat; and the melted pipe leaks from the acoustic absorption holes of the radiation panel.
Therefore, like the ceiling radiation cooling/heating panel disclosed in Patent Document 3, there is proposed the one allowing a noninflammable sheet or a noninflammable plate material to be interposed between a radiation panel and a heat exchange panel, a respective one of which has acoustic absorption holes formed thereon.    Patent Document 1: Japanese Laid-open Patent Application No. 10-232035    Patent Document 2: Japanese Laid-open Patent Application No 2006-170551    Patent Document 3: Japanese Laid-open Patent Application No. 10-227495